While a notebook computer provides superior portability, it is also extremely susceptible to theft. Since recently the tendency is for users at the highest echelons in variety of fields to use computers, and since these users often store valuable information in their computers, most especially in notebook computers, when such a computer is stolen, divulgence of information resources can constitute a much more critical loss than does the loss of the physical resource.
In Japanese Unexamined Patent Publication Nos. Hei 8-50690 and Hei 10-124764, an electronic goods monitoring system is disclosed that uses a non-contact communication technique called an RF (Radio Frequency) transponder system. The RF transponder system generally comprises an Exciter/Reader (ER) and an RFID (Radio Frequency Identification) transponder or an RFID tag. The RFID tag is attached to a product in a monitored area, and the ER is deployed at a portal gate of the area, whereat it constantly generates an RF excitation signal. So that a power source is not required by the RFID tag itself, when the product to which the RFID tag attached is moved near the gate, the ER transmits an excitation signal that provides power for the RFID tag. Upon receiving the RF excitation signal, the RFID tag generates an identification code and other data signals, and, at a specific frequency, transmits them as a response signal to the ER. When the ER detects the identification code included in the response signal, it generates an alarm sound, as needed, to forestall the theft of the product. In order for the product to be removed from the monitored area without the alarm being sounded, the RFID tag must be set to the state whereat it does not transmit an alarm signal, or must be removed from the product.
In Japanese Unexamined Patent Publication No. Hei 5-35354, a technique is disclosed for forestalling theft of a notebook computer. In addition to other devices, the notebook computer comprises theft prevention means, for detecting changes in the installation condition, such as displacement, pressure and distance from an installation location; and means for generating an audible alarm, in accordance with changes in the installation condition. The computer constantly monitors the installation condition, and when, without permission, the computer is moved from a specific location, these means perform their prescribed functions, i.e., an alarm is sounded to prevent theft.
In Japanese Unexamined Patent Publication No. Hei 3-100894, a technique is disclosed whereby when a portable terminal is stolen, key entry is halted and unauthorized terminal accesses are prevented. When a portable terminal is stolen, a host computer transmits a specific radio signal to the terminal and, upon receiving this signal, the anti-theft program in the terminal is activated and key entry is disabled.
As described above, a technique is well known whereby an RFID tag is used to prevent theft of a product. Also well known are the techniques whereby a notebook computer is prevented from being illegally removed from a monitored area and whereby, when a computer is stolen, the keyboard is locked in order to protect information resources. However, no technique has been disclosed for attaching an RFID tag to a computer to prevent unauthorized accesses after the computer has been stolen.
A device, such as an RFID tag, must be provided for a computer in order to prevent theft or unauthorized accesses to stored information. Such devices, however, are not always required by users who purchase computers only for their personal use, as opposed to those users who are company employees and use their computers for company business. Therefore, it is preferable that the security function is not provided for all computers that are available on the market, because users who do not require such a function would have to pay extra for an unneeded capability. Therefore, for a specific computer series, one model must be produced that includes the security function and one model that does not.
To provide low prices and good maintenance services, it is preferable to increase utilization of the same hardware and the same software in both models when two models are produced for a specific computer series. When two models of computer in a specific series, only one having a security function, are manufactured and sold, it would seem that the costs to the users who do not need the security function would be fair. However, the costs are increased for those portions of the hardware and the software that can not be used in common, and as a result, the price is not advantageous for users who do not need the security function. As a result, there is an increased demand that solutions be found for problems concerned with the sharing of hardware and software in two models, and concerned with the fairness of the charges and expenses imposed on users, depending on whether or not a selected model is one that includes the security function.
To resolve these problems, it is preferable that there is a method whereby when a security function is implemented by a plurality of hardware and software components, some of those components are used in common, while the remaining components are optional ones that a dealer or a user can add later, as needed, to incorporate the security function. However, when a device (hereinafter this device is simply called a security device) that serves to implement a part of the security function is installed by a user or a dealer, that security device may be removed illegally, thus negating the security function.
It is, therefore, one object of the present invention to provide a technique by which access to a computer is proscribed when a device that serves as a part of the components required for a security function, i.e., a security device, is illegally removed from a computer. It is another object of the present invention to provide a computer system wherein only a security device is regarded as an optional device for a computer that includes a security function and one that does not, and wherein the other hardware and the software components used in common by the two computers are installed. It is an additional object of the present invention to provide a preferable structure for a security device that can be installed as an optional device by a user or at a dealer.